The invention relates to a device for controlling an electrical signal supplied to the device. More particularly, the invention relates to such a device including a connection socket having a cylindrical recess and also having contact springs for establishing an electrical contact with a cylindrical plug adapted to be received by the cylindrical recess, and further including means for adjusting a rotary control shaft of an electrical component for controlling the electrical signal.
Numerous radio receivers, television receivers or sound reproducing devices comprise one or several connection sockets of the type generally designated as "jacks" (for example, for the output of an audio signal). The connection socket can be provided as the only output of the signal of an apparatus or also as auxiliary output for the signal when the apparatus itself comprises its own reproducing means, notably one or several loudspeakers in the case of sound reproduction.
In all cases, it is necessary in practice to provide a capability for controlling the signal supplied by the connection socket. Such capability is used, for example, for controlling the sound volume and/or the balance in the case of stereophonic signals. A technical solution consists of a control by means of a control knob on the front side of the apparatus. The control is common to the operation of the apparatus in the autonomous mode and to the operation at the auxiliary output. However, this solution is not satisfactory in all circumstances because, for technical reasons or for reasons of commodity, it may be desirable to have a particular control of the signal coming from the auxiliary connection socket. By way of example, the case may be mentioned of a television apparatus which has its own loudspeakers for the sound reproduction and an auxiliary connection socket for an ear-phone. Depending upon the operating conditions, it may be desired that one of the users prefers the ear-phone with a given sound volume and that other users listen simultaneously to the sound reprduced by the loudspeakers of the television apparatus with a sound volume chosen independently of that of the ear-phone. It will then be necessary to utilize a supplementary control for the auxiliary connection socket.
Thus, a considerable increase of the number of control knobs results which not only renders the use of the apparatus more complicated for the user, but also prohibits a further miniaturization of the apparatus and influences its price.
It is known from U.S. Pat. No. 2,986,705 to obtain a control of the signal by a rotatable knob which is coaxial with the connection socket and which transmits through the front of the apparatus the control movement to one or several electrical components by means of gears. Certainly, this solution permits a desirable reduction of the size of the apparatus, but it nevertheless requires a comparatively large number of mechanical parts which results in a price limiting its use. A further disadvantage of the known device with respect to its ease of employment for the user can also be mentioned. Specifically the user has to operate the control knob, while the body of the plug projecting at its center makes the operation somewhat difficult.